docs: def extensions_in_same_folder(file_name):
      """Returns a list of file extensions from the same folder as file_name."""
  
      directory = os.path.dirname(file_name)
      files = os.listdir(directory)
      extensions = list(zip(*map(os.path.splitext, files)))[1]
      extensions = set([ext.lower() for ext in extensions])
      return extensions